Optical properties of BiCr_xFe_1-xO₃ films grown by sol-gel method

The BiCr_xFe_1-xO₃ thin films were fabricated on Si substrate by sol-gel method with x range from 0 to 0.05. X-ray diffraction analysis shows that both pure BiFeO₃ thin film and Cr-doped BiFeO₃ thin films have rhombohedral structure with space group R3c. Moreover, the influence of different values of x on the extinction coefficient and refractive index were investigated in order to exploit their possible application in optoelectronic devices. The optical constants of the Cr-doped BiFeO₃ thin films in the wavelength range 500-1100 nm were obtained by spectroscopic ellipsometry, and the band-gap energy of BiCr _0.03Fe_0.97O₃ was found to be 2.40 ±0.02 eV, and that of BiCr_0.05Fe_0.95O₃ was 2.30 ±0.02 eV.